Wan Yiu Sing grew up in a Cantonese Opera troupe, Dennis was influenced by his father to develop an interest in Cantonese opera. He graduated from the Department of Chinese of Lingnan University and the Youth Class of The Cantonese Opera Academy of Hong Kong organised by The Chinese Artists Association of Hong Kong, he started his Cantnoese Opera career specialising in playing the civil and marshal role (Wenwusheng) and young male lead role (Xiaosheng). With his serious learning attitude and humble personality, predecessors and audiences unanimously praised his appearances and singing in the industry, in recent years, he has been taught by Cantonese opera celebrities Luo Jiaying, Wu Qianfeng and national first-class actor Shi Jihua. He has performed with various professional Cantonese Opera troupes as the young male lead role (Xiaosheng) such as Brilliant Jade Chinese Opera Troupe, Sun Moon Star Cantonese Opera, Kwan and Fung Opera Troupe, Link of Galaxies Cantonese Opera Association, Yue Art Workshop and more. Since 2023, he has also been a guest instructor at Rainbow Cantonese Opera, The Cantonese Opera Academy of Hong Kong, and Kim Sum Cantonese Opera Academy in Hong Kong.